Natriuretic polypeptides (NPs) are polypeptides that can cause natriuresis (increased sodium excretion in the urine). Such polypeptides can be produced by brain, heart, kidney, and/or vascular tissue. The natriuretic peptide family in humans includes the cardiac hormones atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and urodilatin (URO). Natriuretic polypeptides function via well-characterized guanylyl cyclase receptors (i.e., NPR-A for ANP, BNP, and URO; and NPR-B for CNP) and the second messenger cyclic 3′5′ guanosine monophosphate (cGMP) (Kuhn (2003) Circ Res 93:700-709; Tawaragi et al. (1991) Biochem. Biophys. Res. Commun. 175:645-651; and Komatsu et al. (1991) Endocrinol. 129:1104-1106).